What power factor value is used in the 460-volt motor calculation?

What power factor value is used in the 460-volt motor calculation?

• A. 0.70
• B. 0.80
• C. 0.85
• D. 0.90

Answer: (B)

Power factor is used to relate real power to apparent power in motor calculations. For a 460 V motor, a common baseline assumption is a PF of 0.80 (0.80 lagging). This reflects typical full-load behavior of three-phase induction motors and keeps calculations conservative when estimating current. Using PF = 0.80 lets you estimate current from real power with I ≈ P / (√3 × V × PF). If you know horsepower, convert to kilowatts (P = HP × 0.746) and apply the same formula. The 0.80 value is standard unless the motor nameplate provides a different PF; choosing a lower PF (like 0.70) would overstate current, while higher values (0.85–0.90) are less common as defaults.

Power factor is used to relate real power to apparent power in motor calculations. For a 460 V motor, a common baseline assumption is a PF of 0.80 (0.80 lagging). This reflects typical full-load behavior of three-phase induction motors and keeps calculations conservative when estimating current.

Using PF = 0.80 lets you estimate current from real power with I ≈ P / (√3 × V × PF). If you know horsepower, convert to kilowatts (P = HP × 0.746) and apply the same formula. The 0.80 value is standard unless the motor nameplate provides a different PF; choosing a lower PF (like 0.70) would overstate current, while higher values (0.85–0.90) are less common as defaults.